KVM: selftests: Verify VMX MSRs can be restored to KVM-supported values

Verify that KVM allows toggling VMX MSR bits to be "more" restrictive,
and also allows restoring each MSR to KVM's original, less restrictive
value.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220607213604.3346000-16-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

tools/testing/selftests/kvm/.gitignore

@@ -50,6 +50,7 @@
 /x86_64/vmx_dirty_log_test
 /x86_64/vmx_exception_with_invalid_guest_state
 /x86_64/vmx_invalid_nested_guest_state
+/x86_64/vmx_msrs_test
 /x86_64/vmx_preemption_timer_test
 /x86_64/vmx_set_nested_state_test
 /x86_64/vmx_tsc_adjust_test

tools/testing/selftests/kvm/Makefile

@@ -107,6 +107,7 @@ TEST_GEN_PROGS_x86_64 += x86_64/vmx_apic_access_test
 TEST_GEN_PROGS_x86_64 += x86_64/vmx_close_while_nested_test
 TEST_GEN_PROGS_x86_64 += x86_64/vmx_dirty_log_test
 TEST_GEN_PROGS_x86_64 += x86_64/vmx_exception_with_invalid_guest_state
+TEST_GEN_PROGS_x86_64 += x86_64/vmx_msrs_test
 TEST_GEN_PROGS_x86_64 += x86_64/vmx_invalid_nested_guest_state
 TEST_GEN_PROGS_x86_64 += x86_64/vmx_set_nested_state_test
 TEST_GEN_PROGS_x86_64 += x86_64/vmx_tsc_adjust_test

tools/testing/selftests/kvm/include/x86_64/processor.h

@@ -100,6 +100,7 @@ struct kvm_x86_cpu_feature {
 #define	X86_FEATURE_SMEP	        KVM_X86_CPU_FEATURE(0x7, 0, EBX, 7)
 #define	X86_FEATURE_INVPCID		KVM_X86_CPU_FEATURE(0x7, 0, EBX, 10)
 #define	X86_FEATURE_RTM			KVM_X86_CPU_FEATURE(0x7, 0, EBX, 11)
+#define	X86_FEATURE_MPX			KVM_X86_CPU_FEATURE(0x7, 0, EBX, 14)
 #define	X86_FEATURE_SMAP		KVM_X86_CPU_FEATURE(0x7, 0, EBX, 20)
 #define	X86_FEATURE_PCOMMIT		KVM_X86_CPU_FEATURE(0x7, 0, EBX, 22)
 #define	X86_FEATURE_CLFLUSHOPT		KVM_X86_CPU_FEATURE(0x7, 0, EBX, 23)

tools/testing/selftests/kvm/x86_64/vmx_msrs_test.c

+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * VMX control MSR test
+ *
+ * Copyright (C) 2022 Google LLC.
+ *
+ * Tests for KVM ownership of bits in the VMX entry/exit control MSRs. Checks
+ * that KVM will set owned bits where appropriate, and will not if
+ * KVM_X86_QUIRK_TWEAK_VMX_CTRL_MSRS is disabled.
+ */
+#include <linux/bitmap.h>
+#include "kvm_util.h"
+#include "vmx.h"
+
+static void vmx_fixed1_msr_test(struct kvm_vcpu *vcpu, uint32_t msr_index,
+				  uint64_t mask)
+{
+	uint64_t val = vcpu_get_msr(vcpu, msr_index);
+	uint64_t bit;
+
+	mask &= val;
+
+	for_each_set_bit(bit, &mask, 64) {
+		vcpu_set_msr(vcpu, msr_index, val & ~BIT_ULL(bit));
+		vcpu_set_msr(vcpu, msr_index, val);
+	}
+}
+
+static void vmx_fixed0_msr_test(struct kvm_vcpu *vcpu, uint32_t msr_index,
+				uint64_t mask)
+{
+	uint64_t val = vcpu_get_msr(vcpu, msr_index);
+	uint64_t bit;
+
+	mask = ~mask | val;
+
+	for_each_clear_bit(bit, &mask, 64) {
+		vcpu_set_msr(vcpu, msr_index, val | BIT_ULL(bit));
+		vcpu_set_msr(vcpu, msr_index, val);
+	}
+}
+
+static void vmx_fixed0and1_msr_test(struct kvm_vcpu *vcpu, uint32_t msr_index)
+{
+	vmx_fixed0_msr_test(vcpu, msr_index, GENMASK_ULL(31, 0));
+	vmx_fixed1_msr_test(vcpu, msr_index, GENMASK_ULL(63, 32));
+}
+
+static void vmx_save_restore_msrs_test(struct kvm_vcpu *vcpu)
+{
+	vcpu_set_msr(vcpu, MSR_IA32_VMX_VMCS_ENUM, 0);
+	vcpu_set_msr(vcpu, MSR_IA32_VMX_VMCS_ENUM, -1ull);
+
+	vmx_fixed1_msr_test(vcpu, MSR_IA32_VMX_BASIC,
+			    BIT_ULL(49) | BIT_ULL(54) | BIT_ULL(55));
+
+	vmx_fixed1_msr_test(vcpu, MSR_IA32_VMX_MISC,
+			    BIT_ULL(5) | GENMASK_ULL(8, 6) | BIT_ULL(14) |
+			    BIT_ULL(15) | BIT_ULL(28) | BIT_ULL(29) | BIT_ULL(30));
+
+	vmx_fixed0and1_msr_test(vcpu, MSR_IA32_VMX_PROCBASED_CTLS2);
+	vmx_fixed1_msr_test(vcpu, MSR_IA32_VMX_EPT_VPID_CAP, -1ull);
+	vmx_fixed0and1_msr_test(vcpu, MSR_IA32_VMX_TRUE_PINBASED_CTLS);
+	vmx_fixed0and1_msr_test(vcpu, MSR_IA32_VMX_TRUE_PROCBASED_CTLS);
+	vmx_fixed0and1_msr_test(vcpu, MSR_IA32_VMX_TRUE_EXIT_CTLS);
+	vmx_fixed0and1_msr_test(vcpu, MSR_IA32_VMX_TRUE_ENTRY_CTLS);
+	vmx_fixed1_msr_test(vcpu, MSR_IA32_VMX_VMFUNC, -1ull);
+}
+
+int main(void)
+{
+	struct kvm_vcpu *vcpu;
+	struct kvm_vm *vm;
+
+	TEST_REQUIRE(kvm_has_cap(KVM_CAP_DISABLE_QUIRKS2));
+	TEST_REQUIRE(kvm_cpu_has(X86_FEATURE_VMX));
+
+	/* No need to actually do KVM_RUN, thus no guest code. */
+	vm = vm_create_with_one_vcpu(&vcpu, NULL);
+
+	vmx_save_restore_msrs_test(vcpu);
+
+	kvm_vm_free(vm);
+}